Under the 3GPP standards, a NodeB (or an eNB in LTE) is the base station via which mobile devices connect to the core network. Recently the 3GPP standards body has adopted an official architecture and started work on a new standard for home base stations (HNB). Where the home base station is operating in accordance with the (Long Term Evolution) LTE standards, the HNB is sometimes referred to as a HeNB. A similar architecture will also be applied in the WiMAX (Worldwide Interoperability for Microwave Access) network. In this case, the home base station is commonly referred to as a femto cell. For simplicity, the present application will use the term HNB to refer to any such home base station and will use the term NodeB generically to refer to other base stations (such as the base station for the macro cell in which a HNB operates). The HNB will provide radio coverage (for example, 3G/4G/WiMAX) within the home and will connect to the core network via a suitable public network (for example via an ADSL link to the Internet) and in the case of the 3GPP standards, via an optional HNB gateway (HNB-GW) which typically will aggregate traffic from several HNBs.
The HNB may be configured to operate using one of a plurality of access modes, namely: ‘closed’ in which the HNB operates as a closed subscriber group (CSG) cell; ‘hybrid’ in which the HNB operates as a CSG cell where at the same time, non-members are allowed access; and ‘open’ in which the HNB operates as a normal (non-CSG) cell.
When the HNB is in the hybrid access mode, and services cannot be provided to a CSG member due to a shortage of HNB resources, established communications of non-members via a CSG cell may be diverted to another cell. Furthermore, to minimise the impact of non-member established communication on CSG members, the network may allow the data rate of established communication of non-members to be reduced. However, the need to establish the CSG membership status of a particular mobile telephone in order to determine which established connections belong to members, and which belong to non-members has the potential to have a negative impact on already scarce resources. Moreover, when a congested HNB receives new connection requests it may admit requests from non-member devices which may result in an undesirable degradation in service for member devices, or may reject requests from member devices due to a lack of available resources when the congestion is being caused by established connections with non-member devices.